The present invention relates to a parking brake device for a vehicle having a releasing system of a foot-operated type.
Vehicle parking brake devices are largely classified into a hand-operated type and a foot-operated type depending upon the operating form. Foot-operated parking brake devices are being spread mainly among high-grade cars. Many types of foot-operated parking brake devices have been conventionally proposed, and as one of those, a full foot-operated parking brake device in which not only a braking operation (namely, an operation for setting a braking force) but also a releasing operation are conducted by a stepping operation is known.
In a foot-operated parking brake device, there may occur a situation in which, although a braking force is once set by a stepping operation, the amount of stepping is not sufficient and thus a required braking force cannot be obtained. In such a case, an operation for increasing the braking force is required.
However, conventional parking brake devices, in which, when a pedal is further stepped on from an initially set position (so-called xe2x80x9cadditional stepping operationxe2x80x9d), a function of maintaining the pedal position at the moment is released, namely, a braking release operation is conducted, do not have a function of maintaining the pedal at a position after the additional stepping. Thus, when a larger braking force is desired (namely, braking force is desired to be increased) after a braking operation has been conducted to set a braking force, the function of maintaining the pedal position at the moment must be once released to restore the pedal to a set state before the braking operation (namely, the braking force must be vanished). Then, the pedal must be stepped on beyond the initial stepped-on position to a required stepped-on position to set a braking force once again, and an operation for maintaining the condition must be conducted.
As a result, in the conventional parking brake devices, the operation at the time when an increase of the braking force is desired is complicated and thus the operability thereof is poor. Additionally, in the braking force changing operation, the braking force already set is once vanished and a braking force must be set again. Thus, there is no continuity of the braking force before and after the braking force changing operation, resulting in impairment in reliability during operation.
In view of the problems of such a conventional foot-operated parking brake device for a vehicle, the present invention is aimed at improving the operability thereof by allowing a braking force to be increased by an additional stepping operation and enhancing the reliability thereof during operation by securing a continuity of the braking force during the braking force increasing operation.
According to one aspect of the present invention there is provided a parking brake device for a vehicle having brake means, comprising:
a pedal arm (2) having pawl teeth (12) and operatively connected to said brake means such that said brake means performs a braking action when said pedal arm is stepped on;
a latch pawl member (4) including a latch pawl (15) engageable with said pawl teeth (12) of said pedal arm (2), movable between a locked position in which said latch pawl (15) is in locking engagement with said pawl teeth (12) and an unlocked position in which said locking engagement of said latch pawl (15) with said pawl teeth (12) is released, said latch pawl member (4) assuming said locked position, when said pedal arm (2) is stepped on, to maintain said pedal arm (2) in a stepped-on position at the moment and assuming said unlocked position, when said pedal arm (2) is further stepped on from said stepped-on position by a determined amount, to allow said pedal arm (2) to rotate in a direction opposite to the stepping direction thereof;
a position changing member (5) supported on a common support shaft (9) for said latch pawl member (4) and provided with a latch pawl (22) engageable with said pawl teeth (12) of said pedal arm (2), said position changing member (5) being operatively connected to said pedal arm (2) and said latch pawl member (4) and adapted for shifting said latch pawl member (4) from said unlocked position to said locked position by a stepping force applied to said pedal arm (2) when said pedal arm (2) is stepped on by an amount over said determined amount;
a first engaging portion (23) provided on said position changing member (5) and engageable with said latch pawl member (4) when said latch pawl member (4) assumes said locked position to maintain said position changing member (5) at such a position that said latch pawl (22) is separated from said pawl teeth (12) of said pedal arm (2); and
a second engaging portion (24) provided on said position changing member (5) and engageable with said latch pawl member (4) when said latch pawl member (4) assumes said unlocked position to maintain said position changing member (5) at such a position that said latch pawl (22) is engaged by said pawl teeth (12) of said pedal arm (2).
In another aspect, the present invention provides a parking brake device for a vehicle having brake means, comprising:
a pedal arm (42) rotatably mounted on a mounting bracket (41) fixedly disposed on a vehicle body and operatively connected to said brake means such that said brake means performs a braking action when said pedal arm is stepped on;
a pawl teeth member (43) including pawl teeth (52) and fixed to said mounting bracket (41);
a latch pawl member (44) including a latch pawl (55) engageable with said pawl teeth (52) of said pawl teeth member (43), movable between a locked position in which said latch pawl (55) is in locking engagement with said pawl teeth (52) and an unlocked position in which said locking engagement of said latch pawl (55) with said pawl teeth (52) is released, said latch pawl member (44) assuming said locked position, when said pedal arm (42) is stepped on, to maintain said pedal arm (42) in a stepped-on position at the moment and assuming said unlocked position, when said pedal arm (42) is further stepped on from said stepped-on position by a determined amount, to allow said pedal arm (42) to rotate in a direction opposite to the stepping direction thereof;
a position changing member (45) supported on a common support shaft (49) for said latch pawl member (44) and operatively connected to said pedal arm (42) and said latch pawl member (44) for shifting said latch pawl member (44) from said unlock position to said locked position by a stepping force applied to said pedal arm (42) when said pedal arm (42) is stepped on by an amount over said determined amount;
and an engaging portion (64) provided on said position changing member (45) and engageable with said latch pawl member (44) when said latch pawl member (44) assumes said locked position to maintain the position of said position changing member (45), and with said latch pawl member (44) when said latch pawl member (44) assumes said unlocked position to maintain the position of said latch pawl member (44).